2 SITE-SPECIFIC ENDONUCLEASES FROM THE THERMOPHILIC STRAIN BACILLUS SPECIES LU11

A strain containing two restriction endonucleases was found during scr eening of natural strains of thermophilic bacteria. One of these restr iction endonucleases, BspLU11II, proved to be an isoschizomer of XbaI, and the other, BspLU11I, recognizes a new palindromic sequence 5'-A d own arrow CATGT-3' and cleaves it as shown by the arrow. Functionally pure enzyme preparations were obtained by successive chromatography on columns with blue agarose, HA-Ultragel, and heparin-Sepharose. Restri ction endonuclease BspLU11I gives ''sticky'' ends identical to the end s produced by restriction endonuclease NcoI. consequently, BspLU11I an d NcoI can both be used for enzymatic selection of recombinant DNA. Th e ATG codon is included in the recognized BspLU11I sequence and expres sive vectors for chemically synthesized genes can be constructed on it s basis.